Many hydrocarbon streams such as natural gas streams, refinery processing gas streams (e.g., tail gas streams), synthesis gas streams, etc., are contaminated with sulfur-containing acid gases such as hydrogen sulfide, sulfur dioxide, mercaptants, sulfides, carbon dioxide, etc. It is important to remove the acid gas impurities from such streams in order to enhance their utility and also to avoid environmental pollution. It is common practice to use a liquid absorption process to remove the acid gases wherein a solvent, such as an alkanolamine, which has a selective absorption capacity for the acid gases is brought into counter-current contact with the gas stream to be treated on a continuous basis in an absorption zone. The at least partially purified gas stream is discharged from the absorption zone for further processing while the solvent, rich in absorbed gases, is discharged from the absorption zone and then charged to a regeneration zone wherein the acid gases are removed from the rich solvent solution to thereby provide a lean solvent solution for recycle to the absorption zone and a stream of desorbed acid gases.
It is frequently desirable to use the desorbed stream of acid gases, when they are rich in sulfur, as a feedstock for the production of elemental sulfur in an appropriate processing unit such as a Clauss unit. It is also frequently desirable to use carbon dioxide for a secondary hydrocarbon recovery process.
In accordance with the present invention, a process is provided for separating the carbon dioxide from the sulfur-containing acid gas components, principally H.sub.2 S, in order to enhance the utility of the carbon dioxide stream for use in secondary recovery operations and in order to enhance the value of the sulfur-containing stream as a feedstock for a Clauss unit.